Component V - Topiramate Treatment of Problem Drinkers The proposed study is a 12-week trial comparing topiramate (TOP), at a dosage of 200 mg/day, with an inactive placebo. We will randomly assign 160 problem drinkers (i.e., heavy drinkers without evidence of physical dependence on alcohol) who want to reduce their drinking. It is estimated that 30% of the general population are problem drinkers (NIAAA 2007). Despite its high prevalence, problem drinkers are understudied, particularly with respect to medications that may help them to reduce their drinking to safe levels. The study will extend to this patient population findings from a trial of TOP, which showed the drug to be well tolerated and efficacious in moderately-severe alcohol-dependent patients (Johnson et al. 2003). The aims of the present study are to examine: 1) TOP'S safety and efficacy in reducing drinking and heavy drinking, 2) the relations among medication, daily mood, expectancies, and drinking behavior, and 3) the durability of TCP's effects during a six-month post-treatment follow-up period. A fourth, exploratory aim, is to estimate the effect size of variation in genes encoding GABA and glutamate receptors as moderators of both the therapeutic and adverse effects of TOP. The study will use interactive voice response technology to collect daily measures of drinking, mood, and medication usage. Biological measures of alcohol consumption (i.e., GGTP and CDT) will be used to validate self-reports. Hierarchical linear modeling will be used to examine effects at the between-person and within-person levels of analysis. Careful evaluation of the study's hypotheses will provide important information on the efficacy and mechanism of effects of TOP as a treatment for problem drinkers.